Electro-Optical (EO) components, like single mode transmitter/receiver optical sub-assemblies used in transmitters and receivers in fiber communication, are usually packaged utilizing transistor outline construction (sometimes referred to as a “TO can”). The EO components inside a TO can are wire-bonded to a number of leads that protrude through the package and allow signals to be routed to the EO components. These leads are bent and soldered onto a PCB board that contains the electronic components and circuitry to drive the EO components.
A TO can has several disadvantages. The packaging process requires significant human labor with multiple alignment processes. Current methods are very much cottage industry like—often described a being akin to building a ship in a bottle. A large fraction of the cost of single mode transmitter/receiver optical subassemblies is associated with the packaging process.
The leads on known TO can structures are typically a few millimeters in length and can cause a degradation of the frequency response of the subassembly. The leads also have to be bent and soldered onto the PCB board. This process is difficult to automate and is typically performed by hand. Yet another disadvantage is the mechanical tolerances stack up, e.g. the tolerance for the lens placement is affected by die placement. This requires that each component be positioned using a dedicated three-alignment system: one for die placement; one for lens placement; and one for the receptacle.
The present inventors have recognized a need for an electro-optical subassembly wherein the packaging process can be automated while avoiding at least some of the disadvantages of known TO cans.